1. Field of the Invention
The present invention concerns a diaper comrising a flexible outer film impermeable to liquids, longitudinal strips of adhesive on an inside surface of said outer film, an absorbent pad on said inside surface of said outer film having longitudinal edges set back from longitudinal edges of said outer film and transverse edges set back from transverse edges of said outer film, a flexible inner film permeable to liquids covering said inside surface of said outer film and said absorbent pad thereon and adhesively bonded to said outer film in the area of contact between said films around said pad, longitudinal elastic members adhesively bonded while tensioned onto the outside surface of said outer film along a median part of its longitudinal edge portions, and attachment means for fastening the diaper around the body of the wearer.
The invention also concerns a method for continuous manufacture of such diapers.
2. Description of the Prior Art
The known method for continuous manufacture of diapers of the above-defined type consists in the steps of:
unwinding a continuous strip of film impermeable to liquids, PA1 unwinding continuous elastic members, applying adhesive to said elastic members at intervals so as to obtain adhesive coated sections separated by sections not coated with adhesive, and applying said elastic members while tensioned to the upper surface of the impermeable film between lines of adhesive near the two longitudinal edge portions of the film, so as to adhesively bond the elastic members at successive spaced sections of the impermeable film, PA1 placing successively onto the upper surface of the impermeable film fitted with the elastic members individual absorbent pads having a width less than the width of the film so that the successive pads are placed on the film in the areas where the elastic members adhere to the latter and are spaced from each other in the direction of the length of the impermeable film, PA1 unwinding a continuous strip of film permeable to liquids having the same width as said impermeable film, applying adhesive to said permeable film on one side thereof and applying said adhesive coated side thereof to the upper surface of the impermeable film previously fitted with the elastic members and absorbent pads, and PA1 cutting successively in the transverse direction the two films and the tensioned elastic members, between the spaced consecutive pads, that is to say in the sections of the elastic members that are not coated with adhesive. PA1 unwinding two spaced continuous tapes of film; PA1 applying continuously to an upper surface of said tapes continuous strip or strand elastic members to parts at least of which adhesive has been previously applied and which are stretched to an appropriate tension; PA1 unwinding a continuous strip of film impermeable to liquids; PA1 applying continuously to a lower surface of said continuous impermeable film said two continuous tapes and said elastic members adhesively bonded to them; PA1 applying continuously transversely spaced longitudinal strips of adhesive to an upper surface of said continuous impermeable film; PA1 placing absorbent pads on said upper surface of said continuous impermeable film; PA1 unwinding a continuous strip of film permeable to liquids having substantially the same width as said continuous impermeable film and applying said permeable film to an upper surface of said impermeable film so that said permeable film adheres to said impermeable film all around said absorbent pads; and PA1 cutting the resulting assembly transversely between consecutive absorbent pads.
On making the transverse cuts which produce the individual diapers the initially continuous and tensioned elastic members are cut so that the parts of the elastic members disposed on each diaper on either side of the adhesive coated sections, adhering to the impermeable film, contract (i.e. relax), whereas the adhesive coated sections adhering to the outer film contract with said film to confer on the latter, in the crotch area of the diaper, the elasticity required to ensure a good fit to the body of the wearer and a good seal.
However, to enable relaxation of the parts of the elastic members not coated with adhesive on such cutting, it is also necessary to prevents these parts adhering to the adhesive coated permeable film. This is why until now areas not coated with adhesive have been provided, when applying adhesive to the permeable film, at the locations of the sections of the elastic members not coated with adhesive prior to cutting.
This produces in the area of the diaper between the spaced transverse edges of the absorbent pad and the permeable and impermeable films "tunnels" extending between the two films from the transverse edges of the pad to the transverse edges of the film, so that the space between the two films and containing the absorbent pad communicates with the exterior. These "tunnels" not only promote the escape to the exterior, by virtue of a draining effect, of urine absorbed by the pad, but also enable the material of the pad to escape to the exterior. This is the case, for example, with absorbent pads made from defibered cellulose pulp, and in particular with pads containing granular superabsorbent material which, although generally incorporated into some other material, such as defibered cellulose pulp, for example, is often readily detached from the absorbent pad and can, by escaping through these "tunnels", reach the exterior where, given its presentation as very small and light grains when dry, it can have unwanted or even harmful effects for the wearer.
French patent application No. 86 16 844 teaches the use of longitudinal tapes on the inside surface of the impermeable film of the diaper at the location of the elastic members so as to define "tunnels" into which the material of the absorbent pad placed over these ribbons cannot enter because the tunnels are only open at the transverse edges of the diaper.
It also teaches making the tapes forming the tunnels from a material impermeable to liquids so as to avoid any migration of liquid through these tunnels which are therefore isolated.
An object of the present invention is a diaper of the above-defined type in which the risk of the material of the absorbent pad escaping to the exterior is prevented with certainty. Another object of the invention is a diaper of the above-defined type in which the escape to the exterior at the longitudinal edges of the diaper of liquids absorbed by the pad of the diaper is prevented or at least strongly reduced. A further object of the invention is a diaper in which the risk of liquid escaping from the lateral (longitudinal) edges of the absorbent pad is prevented or at least strongly reduced.
A final object of the invention is a method for continuous manufacture of such diapers.